Thermal extraction apparatus with high volume sampling trap

ABSTRACT

In an example, a thermal extraction apparatus includes: a housing having a gas inlet and a gas outlet to receive a gas flow through the housing from the gas inlet to the gas outlet, and a side opening to receive a sample collector, having a sample collector adsorbent containing a vapor sample, into a sample collector location; a pump to generate the gas flow; a heater to heat the sample collector adsorbent of the sample collector to a temperature sufficient to release the vapor sample; a thermal desorption (TD) tube connected with the gas outlet of the housing to receive the gas flow downstream of the sample collector and collect the vapor sample released from the sample collector adsorbent of the sample collector; and a cooling member in heat exchange with the TD tube to cool the TD tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a divisional of and claims the benefit of U.S. patentapplication Ser. No. 17/162,984, entitled HIGH VOLUME SAMPLING TRAPTHERMAL EXTRACTION DEVICE, filed on Jan. 29, 2021, which claims priorityfrom U.S. Provisional Patent Application No. 63/052,674, filed on Jul.16, 2020, entitled HIGH VOLUME SAMPLING TRAP THERMAL EXTRACTION DEVICE,the entire disclosures of which are incorporated herein by reference.

SUMMARY STATEMENT OF GOVERNMENT INTEREST

The present invention was made by employees of the United StatesDepartment of Homeland Security in the performance of their officialduties. The U.S. Government has certain rights in this invention.

FIELD

The discussion below relates generally to systems and methods forhigh-volume sampling and, more specifically, to a thermal extractiondevice (TED) to thermally extract materials collected by a particle andvapor collection device such as a high volume sampling trap (HVST).

BACKGROUND

Sampling devices, specifically those used to screen large number ofpeople or items, have been used for some time. These devices can befound almost anywhere, including government-run office buildings andairports. For example, airports use body scanners, utilizing machinesthat allow security officers an unobstructed view of a person's body todetermine the presence of weapons. Other methods test for less visibleitems or substances, such as explosive residue or narcotics.Specifically, much focus has been put towards detection methods forthese less visible substances as terrorism has risen, inasmuch asexplosives, biochemical weapons, and the like threaten the security ofthe United States.

Liquid preparations have been used in detection methodologies. Forexample, a liquid is first applied to a surface to solvate or otherwiseplace into liquid phase the substance of interest which may be residingon the surface. Then, that mixture is tested. While such samplingdevices are reliable, they suffer from many disadvantages, one of whichis efficiency. Generally, in high volume situations it would take toomuch time to prepare liquid samples for every surface requiring testing.

Some detection systems require encapsulating the entire object, thesurfaces of which require sampling. These systems involve largechambers, and therefore require a large footprint in which to operate.Handheld sampling wands also exist. However, many of these wands aretethered to stationary detection units, thereby hindering an operator'smovement when climbing over parcels and crates. Other detection systemsinclude vapor deposition systems whereby adsorbents sequester vaporscontaining target moieties. Such systems often do not allow forsimultaneous extraction and sequestration of solid phase and/or liquidphase samples.

U.S. Pat. No. 8,578,796 to Cho discloses a device for sampling surfacesfor the presence of compounds, including a housing having a proximal endadapted to receive a negative pressure gradient and a distal end adaptedto contact the surfaces; a heating element spaced from the distal end; aprimary filter spaced from the heating element; and a secondary filterspaced from the primary filter, the secondary filter removably receivedby the housing. A method for sampling a surface for the presence ofcompounds includes contacting the surface to dislodge the compounds fromthe surface; capturing first fractions of the compounds with a primaryfilter while allowing second fractions of the compounds to pass throughthe primary filter; heating the primary filter to volatilize the firstfractions; capturing the volatized first fractions and the secondfractions with a secondary filter; and analyzing the secondary filter toidentify the compounds. The detection system is portable or stationary,light weight, and low cost. It utilizes off the shelf componentry, iscapable of simultaneous sequestration of multi-phases of targetcompounds, and allows continued sequestration of target compounds in thefield by facilitating in situ replacement of full sample carriers withempty ones.

SUMMARY

Embodiments of the present invention are directed to apparatuses andmethods for thermally extracting vapor samples collected with a sampletrap using a thermal desorption (TD) collector such as a TD tube, whichcan then be inserted into a mass spectrometer for direct sampleanalysis. One example of the sample trap is the secondary filterdisclosed in U.S. Pat. No. 8,578,796 which also employs a primary filterto capture relatively large particles and a heater to heat and vaporizethe captured particles. An adsorbent resin, as a sample collectoradsorbent in the sample trap, collects the vaporized sample. See, e.g.,U.S. Pat. No. 8,578,796 at column 7, line 18 to column 8, line 67 and inFIGS. 5 and 6, which is incorporated herein by reference. In anotherembodiment, the sample trap including an adsorbent resin is used tocollect vapor-phase particle sample and potentially micrometer-sizedparticle sample, by adapting it to a vacuum device, without using theprimary filter and heater. The sample trap may be referred to as a highvolume sampling trap (HVST), which can be used to collect a large volumeof the air samples from cargo container freight, palletized cargo, andsecurity checkpoint to trap illicit organic volatile materials. Thevacuum device is light-weight and portable, and can be used in otherapplications, such as sample collection at airports or othercheckpoints, which involve smaller volumes of air sample collection.

The sample trap is placed into a TED, which may be referred to as anHVST-TED. The device may include a heater to heat the sample trap toabout 200° C. and a gas flow is used to move the heated vapor-phasesample and any semi-volatile organic compound sample to a TD collectorsuch as a TD tube disposed downstream. The TD tube may be cooled toabout 0-10° C. for collecting the vapors and analytes. The use of the TDtube facilitates direct analysis on a mass spectrometer to identify thechemical species released from the sample trap, by removing the TD tubefrom the TED and inserting it directly into a Thermal Desorption-GasChromatography/Mass Spectrometer (TD-GC/MS) for sample analysis. Assuch, the HVST desorber has been modified for better sample recovery ona TD tube. The use of the TD tube provides a one-step analysis of thetrapped sample.

In accordance with one aspect, a thermal extraction apparatus comprises:a housing having a gas inlet and a gas outlet to receive a gas flowthrough the housing from the gas inlet to the gas outlet, and a sideopening to receive a sample collector into a sample collector location,the sample collector having a sample collector adsorbent containing avapor sample; a pump to generate the gas flow; a heater to heat thesample collector adsorbent of the sample collector to a temperaturesufficient to release the vapor sample; a TD tube connected with the gasoutlet of the housing to receive the gas flow downstream of the samplecollector and collect the vapor sample released from the samplecollector adsorbent of the sample collector; and a cooling member inheat exchange with the TD tube to cool the TD tube.

In accordance with another aspect, a thermal extraction apparatuscomprises: a housing having a gas inlet and a gas outlet to receive agas flow through the housing from the gas inlet to the gas outlet, andan insertion port to receive a sample collector having a samplecollector adsorbent containing a vapor sample; a pump to generate thegas flow; a heating mechanism for heating the sample collector adsorbentof the sample collector to a temperature sufficiently high to facilitaterelease of the vapor sample from the sample collector adsorbent of thesample collector; and a TD tube connected with the gas outlet of thehousing to receive the gas flow downstream of the sample collector andcollect the vapor sample released from the sample collector adsorbent ofthe sample collector.

In accordance with yet another aspect, a thermal extraction methodcomprises: placing a sample collector, which has a sample collectoradsorbent containing a vapor sample, inside a housing via a sideopening; heating the sample collector adsorbent of the sample collectorto a temperature sufficiently high to facilitate release of the vaporsample from the sample collector adsorbent and directing a gas flowthrough a gas inlet of the housing through the sample collectoradsorbent of the sample collector through a gas outlet of the housing toa TD tube connected with the gas outlet of the housing to receive thegas flow downstream of the sample collector and collect the vapor samplereleased from the sample collector adsorbent of the sample collectorinside the TD tube.

Other features and aspects of various examples and embodiments willbecome apparent to those of ordinary skill in the art from the followingdetailed description which discloses, in conjunction with theaccompanying drawings, examples that explain features in accordance withembodiments. This summary is not intended to identify key or essentialfeatures, nor is it intended to limit the scope of the invention, whichis defined solely by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached drawings help explain the embodiments described below.

FIG. 1 is a cross-sectional view of a high volume sampling trap thermalextraction device (HVST-TED) according to an embodiment of the presentinvention.

FIG. 2 shows an elevational view of a main housing of the HVST-TEDaccording to another embodiment.

FIG. 2A shows a side view A-A of the main housing of FIG. 2.

FIG. 2B shows a side view B-B of the main housing of FIG. 2.

FIG. 3 shows an exploded perspective view of the main housing of FIG. 2and a secondary housing coupled to the proximal side of the mainhousing.

FIG. 4 shows an elevational view of the secondary housing of FIG. 3.

FIG. 4A shows a side view A-A of the secondary housing of FIG. 4.

FIG. 5A shows a side view of the left holder according to an embodiment.

FIG. 5B shows a front elevational view of the left holder.

FIG. 5C shows a front elevational view of the right holder according toan embodiment.

FIG. 5D shows a side view of the right holder.

FIG. 6 shows an example of a sample trap, a left holder, and a rightholder of a sample trap assembly.

FIG. 7 shows the sample trap assembly of FIG. 6.

FIG. 8 shows an example of an assembled HVST-TED.

FIG. 9 shows an example of an assembled HVST-TED illustrating connectionto a thermal desorption (TD) tube.

FIG. 10 shows a view illustrating the insertion of the sample trapassembly into the main housing via a side opening.

FIG. 11 shows another view illustrating the insertion of the sample trapassembly into the main housing via the side opening.

FIG. 12 is a schematic view of an example of a TD tube.

FIG. 13 shows an example of an external housing for the HVST-TED.

FIG. 14 shows an example of a thermal extraction system including theHVST-TED and external housing of FIG. 13.

DETAILED DESCRIPTION

A number of examples or embodiments of the present invention aredescribed, and it should be appreciated that the present inventionprovides many applicable inventive concepts that can be embodied in avariety of ways. The embodiments discussed herein are merelyillustrative of ways to make and use the invention and are not intendedto limit the scope of the invention. Rather, as will be appreciated byone of skill in the art, the teachings and disclosures herein can becombined or rearranged with other portions of this disclosure along withthe knowledge of one of ordinary skill in the art.

In large volume sampling, a high volume sampling (HVS) device is adaptedto be in fluid communication with a target such as a ventilation port ofa cargo container such that, for example, the device is placed upstreamor downstream of the ventilation port, or perhaps within and coaxial tothe port. In one example, the HVS device is a vacuum device, which maybe portable, for directing a flow of sample through a sample trapcontaining an adsorbent for trapping vapor-phase sample and anysemi-volatile organic compound sample. The sample trap, which may bereferred to as an HVS trap or H-trap, is then placed into a thermalextraction device (TED). The HVS device can be applied to the breakbulk, pelletized or containerized air/sea cargo. Also, the device can beutilized on chemical and biological warfare agent samples, industrialtoxic chemicals, explosives particle samples, and drugs or hazardouswaste sampling. The HVS device facilitates large volume of air samplecollection from a large screening area. The military explosive,Composition C-4, can be used as a standard explosive for the deviceparticle sample testing. Vapor Sample C-4 includes Triacetonetriperoxide (TATP) and Ethylene glycol dinitrate (EGDN).

Generally, the TED includes a heating device such as a heating cartridgefor heating the sample trap and a thermal desorption collector such as aTD tube positioned downstream of the sample trap. The TD tube mayinclude a polymer adsorbent to trap vapor samples. The heating cartridgeand sample trap are supported by a housing so as to be substantiallyencased by the housing.

In an embodiment, the sample trap is heated to evaporate the targetcompounds that are trapped. The vaporized compounds are directed by agas flow from the sample trap to the TD tube to be re-trapped in the TDtube. During the process, about 1 to 4 L/min of flow, for example, willbe applied to the sample trap for carrying target moieties from thesample trap to the TD tube.

In an embodiment, an aluminum housing holds a removable sample trap anda heater to heat the sample trap. A TD tube is spaced from and disposeddownstream of the sample trap along a gas flow to collect vapor-phasesample and any semi-volatile organic compound sample. In one example,heating members such as heating cartridges are provided upstream anddownstream of the sample trap to generate a temperature gradient that ishigher upstream of the sample trap and lower downstream of the sampletrap.

In one example, the TD tube, comprised of a polymer adsorbent materialsuch as Tenax, collects vapors and analytes from the sample trap afterthe sample trap is heated up to about 200° C. within about 60-120seconds to vaporize some of the particles and analytes collected fromthe sample trap. The TD tube is cooled to about 0-10° C. for collectingthe vapors and analytes. The TD tube is then easily removed and inserteddirectly into a Thermal Desorption-Gas Chromatography/Mass Spectrometer(TD-GC/MS) for sample analysis.

FIG. 1 is a cross-sectional view of a high volume sampling trap thermalextraction device (HVST-TED) 100 according to an embodiment of thepresent invention. The device 100 includes a main housing 104 and asecondary housing 106 connected to a proximal end of the main housing104. In some embodiments, the secondary housing 106 is disposed at leastpartially or completely inside the main housing 104. Along the directionof gas flow from an inlet at the distal end 108 toward a proximal end146 of the secondary housing 106, disposed inside the main housing 104are a heater 110 (including a hot plate 112 in the embodiment shown), aright holder 118, a sample trap or collector 120, and a left holder 122.The gas can be air. The right holder 118, sample trap 120, and leftholder 122 form a sample trap assembly 124 that can be inserted into andremoved from the main housing 104. Downstream of the left holder 122 isa downstream frustoconical cavity 130 of the secondary housing 106 whichcontracts in cross-sectional area in the downstream direction and leadsto a TD collector 140 connected to the proximal end 146 of the secondaryhousing 106 via a proximal connector 150. One example of the TDcollector 140 is a TD tube 140 wrapped around by a cooling coil ortubing 160 having a flow of cooling fluid such as liquid nitrogen (LN2)for cooling the TD tube 140 by heat exchange. The gas flow exits at aproximal end 170 of the device 100, which in one embodiment is connectedto a vacuum pump. This is one means for cooling the TD tube. Othercooling means or mechanisms may be used for cooling the TD tube in otherembodiments.

High volume sampling encompasses sample volumes as high as approximately400 liters per minute of air using a 1-inch inner diameter inputaperture such as a 1″ ID sample tube connected at the distal end 108.Higher sample volumes are attainable if input diameters increase. Eitherthe distal end 108 of the device 100 may be adapted to receivepressurized effluent or the proximal end 170 of the device 100 may beadapted to establish fluid communication with negative pressure (i.e., avacuum pull). In one example, a vacuum pull is established between theproximal end 170 and a vacuum line via a snap fit assembly or threadedconnectors. The proximal end 146 of the secondary housing 106 defines a¼″ Teflon ferrule with a compression fitting nut to effectuate anegative pressure pull with a vacuum hose.

Prior to thermal extraction, the sample trap assembly 124 may beattached to a commercial vacuum system with some modifications tocollect target sample. For instance, the vacuum system may be adapted tobe in fluid communication with a target such as a ventilation port of acargo container. Examples of the vacuum system include the DaytonBackpack Vacuum system (Model 4TRI0) and the Dyson handheld vacuumsystem (Model V6).

FIG. 2 shows an elevational view of a main housing of the HVST-TEDaccording to another embodiment. FIG. 2A shows a side view A-A of themain housing of FIG. 2. FIG. 2B shows a side view B-B of the mainhousing of FIG. 2. The main housing 204 includes a proximal internallythreaded section 210 for receiving a secondary housing similar to thesecondary housing 106 of FIG. 1 on the proximal side. The main housing204 includes a distal internally threaded section 220 for connecting toan air intake at the distal end 208. The main housing 204 has a sideopening or slot 230 which is a complementary aperture or insertion portformed along a longitudinally extending surface of the main housing 204for receiving the sample trap assembly 124 into a sample collectorlocation in the main housing 204. The side opening 230 defines a planewhich is positioned transverse to the longitudinal axis of the mainhousing 204. The main housing 204 has an upstream frustoconical cavity234 that expands in cross-sectional area from the distal internallythreaded section 220 near the distal end 208 in a downstream directiontoward the proximal internally threaded section 210 near the proximalend of the main housing 204.

In the embodiment shown in FIG. 2, instead of a hot plate 112 in FIG. 1,heating cartridges 242, 244 may be provided in the main housing 204 forheating and RTD (resistance temperature detector) probes 252, 254 may beprovided in the main housing 204 for measuring temperature. Thesecomponents are commercially available and are cylindrical in shape. Theupstream heating cartridge 244 and upstream RTD probe 254 are disposedupstream of the sample trap assembly 124 that is inserted into the sideopening 230. The downstream heating cartridge 242 and downstream RTDprobe 252 are disposed downstream of the sample trap assembly 124. Inone example, the upstream heating cartridge 244 and upstream RTD probe254 each have a dimension of about 2″ in length X ¼″ in OD and thedownstream heating cartridge 242 and downstream RTD probe 252 each havea dimension of about 1″ in length X ¼″ in OD. Also, thermometers otherthan RTD probes are used in other embodiments. The hot plate 112 andheating cartridges 242, 244 are example means for heating the samplecollector adsorbent in the sample trap assembly 124. Other heating meansor mechanisms for heating the sample collector adsorbent may be usedinstead of the examples described herein.

The heating cartridges 242, 244 and RTD probes 252, 254 are seen asbeing reversibly or releasably attached to the main housing 204.However, heating cartridges and RTD probes are integrally molded to themain housing 204 in another embodiment. The main housing 204 is heatedat the start of the thermal extraction process.

FIG. 3 shows an exploded perspective view of the main housing 204 ofFIG. 2 and a secondary housing 306 coupled to the proximal side of themain housing 204. The main housing 204 includes the side opening 230 forreceiving the sample trap assembly 124. It is cylindrical so as to allowfor easy manipulation by a single hand of a user. Other shapes are alsoenvisioned. The secondary housing 306 has a proximal end 346 andincludes a distal externally threaded section 320 for engaging with theproximal internally threaded section 210 of the main housing 204 shownin FIG. 2.

FIG. 4 shows an elevational view of the secondary housing 306 of FIG. 3.FIG. 4A shows a side view A-A of the secondary housing of FIG. 4. Thesecondary housing 306 may include a downstream frustoconical cavity 430,similar to the downstream frustoconical cavity 130 of FIG. 1, whichcontracts in cross-sectional area from the distal end of the secondaryhousing 306 toward the proximal end 446. It may include a proximalinternally threaded section 420 for receiving a proximal connectorsimilar to the proximal connector 150 of FIG. 1 for connecting to a TDtube. It may have a distal externally threaded section 410 for engagingthe proximal internally threaded section 210 of the main housing 204 ofFIG. 2.

FIG. 5A shows a side view of the left holder 122 according to anembodiment. FIG. 5B shows a front elevational view of the left holder122. FIG. 5C shows a front elevational view of the right holder 118according to an embodiment. FIG. 5D shows a side view of the rightholder 118.

FIG. 6 shows an example of the sample trap 120, the left holder 122, andthe right holder 118 of the sample trap assembly 124. The left holder122 is matingly received by the right holder 118 to form an interiorspace to receive the sample trap 120. The interior space has a depthmeasuring approximately the thickness of the sample trap 120. The leftholder 122 and the right holder 118 may at least substantiallycompletely encase the sample trap 120. The sample trap 120 may includean adsorbent resin used to collect vapor-phase sample and anymicrometer-sized particle sample prior to being inserted into the mainhousing 206 via the side opening 230 for thermal extraction.

FIG. 7 shows the sample trap assembly 124 of FIG. 6 in assembled form.

FIG. 8 shows an example of an assembled HVST-TED. The main housing 204is connected to the secondary housing 306, and sample trap assembly 124is inserted into the main housing 204 via the side opening 230. Airenters via the distal end of the main housing 204, flow through thesample trap assembly 124, and exits via the proximal end of thesecondary housing 306.

FIG. 9 shows an example of an assembled HVST-TED illustrating connectionto a TD tube. The side opening 230 in the main housing 204 for receivingthe sample trap assembly 124 is more clearly shown. The TD tube 140 isconnected to the secondary housing 306 via a proximal connector 950similar to the proximal connector 150 of FIG. 1. In this example, agraphite ferrule 910 and a thumb wheel 920 are used to tighten theconnection between the proximal connector 950 and an inlet end of the TDtube 140. The outlet end of the TD tube may be connected to a vacuumpump.

FIG. 10 shows a view illustrating the insertion of the sample trapassembly 124 into the sample collector location 1010 of the main housing204 via the side opening 230. FIG. 11 shows another view illustratingthe insertion of the sample trap assembly 124 into the sample collectorlocation 1010 of the main housing 204 via the side opening 230. Thesample collector location 1010 of the main housing 204 may be configuredwith the shape and size to receive the sample trap assembly 124 andalign it automatically to the gas flow path in the main housing 204.Inserting and removing the sample trap assembly 124 can be done quicklyand precisely.

Sample Trap

An embodiment utilizes stainless steel mesh as a constituent of thesample trap 120. The sample trap 120 is a filter made of a meshstainless steel screen and can be heated to about 200° C. or higher tovaporize materials on its surface. The thermal desorption process mayoccur within about 20 seconds, or between about 5 and 15 seconds, orbetween about 5 and 10 seconds. The thermal desorption may beaccompanied with a gas flow through the device 100 so as to directdesorbed moieties from the sample trap 120 to the TD collector 140. Thegas flow rates may range from approximately 50 cc/minute for about fourminutes to about 100 cc/minute for about two minutes.

An embodiment of the sorbent entity comprises 200 mesh (approximately 74microns) stainless steel with between 75 and 200 milligrams of Tenax-GRbacked therein. The trap materials (i.e., resin) are placed in betweenthe two stainless steel wire cloth or fiberglass substrates; then, a tapwelding machine is utilized to weld the edges of the cloth together,thereby substantially encapsulating the trap materials within the wirecloth. Generally, when Tenax-GR resin is utilized, its mesh size may bebetween 80 and 100 or particle sizes having diameters of between about180 microns and 145 microns. When Tenax TA resin is used, its mesh sizemay be between about 60 and 80.

A specific embodiment of the sample trap 120 includes a stainless steel200 mesh. Particle sizes of the adsorbent resin may be about 150 to 250μm. The sample trap 120 can utilize a mesh portion composed ofalternative materials that are inert or non-reactive with the targetcompounds. For any sample trap 120, in order to accommodate theadsorbent resin particles, the stainless steel mesh is typically smallerthan the adsorbent particles.

Thermal Desorption Collector

The TD collector 140 is capable of collecting vapor and anymicrometer-sized particles simultaneously. In an embodiment, the TDcollector 140 includes an adsorbent such as porous polymer resin. Anexample is diphenylene-oxide on a heat-resistant substrate such asgraphite. Tenax-GR and Tenax-TA resins are available through ScientificInstrument Services of Ringoes, N.J. Other suitable resins includeSupelco (Sigma-Aldrich), Restek, Perkin-Elmer, Agilent, and combinationsthereof.

FIG. 12 is a schematic view of an example of a TD tube 140. From thesampling inlet 1210 to the sampling outlet 1212 are disposed a glassfrit 1220, Tenax-TA 1230, glass wool 1240, Carboxen-1003 1250, glasswool 1260, and a stainless-steel screen 1270 (e.g., having a mesh sizebetween about 60 and 80). Tenax-TA 1230 is a porous material based on2,6-diphenylene oxide polymer. It is used to trap volatile andsemi-volatile compounds with an upper temperature limit of about 320° C.It has a low affinity for water or methanol. Water has a very lowbreakthrough value on Tenax adsorbent. Typically, a carbon molecularsieve is used as a backup adsorbent when sampling for very volatileanalytes for example, smaller than dichloromethane. Carboxon 1003 is acarbon molecular sieve 1250 with a large surface area and hydrophobicsurface characteristics, which provide a combination of efficientabsorption/desorption and good hydrophobicity.

Thermal Extraction System

FIG. 13 shows an example of an external housing 1310 for the HVST-TEDhaving a gas flow inlet at the distal end 208. A temperature controlunit 1320 is provided to control the temperature of the main housing 204in which the sample trap 124 is removably placed. For example, thetemperature control unit 1320 is coupled with the downstream heatingcartridge 242 and the upstream heating cartridge 244 of the main housing204 in FIG. 2 for heating and the downstream RTD probe 252 and theupstream RTD probe 254 for measuring the temperature. The temperaturecontrol unit 1320 uses the temperature measurement from the RTD probesas feedback for controlling thermal outputs of the heating cartridges toachieve the desired temperatures. Various temperature control units(TCUs) are commercially available. Any suitable unit can be used oradapted to be used as means or a mechanism for controlling thetemperature of the heating members.

FIG. 14 shows an example of a thermal extraction system 1400 includingthe external housing 1310 for the HVST-TED and the temperature controlunit 1320 of FIG. 13. The system 1400 includes an inlet flow line 1404into and an outlet flow line 1406 out of the HVST-TED inside theexternal housing 1310, and the cooling coil 160 wrapped around the TDtube 140. The LN2 cooling temperature is below set point (10° C.) aroundthe TD tube 140. The outlet flow line 1406 is a low-flow TD samplingpump line (negative pressure) connected to the sampling outlet 1212 ofthe TD tube 140 in FIG. 12. In one example, the gas flow rate is set atabout 50-100 cc/minute for about 2-4 minutes, while the temperaturecontrol unit 1320 is set at about 200° C. near the distal end 208 andabout 190° C. near the proximal end of the main housing 204 in FIG. 2.

At the start of an example process, the sample trap 120 has collectedtherein gas phase moieties and potentially micrometer-sized particlesamples from a target area. The sample trap 120 is placed inside themain housing 204 of the HVST-TED, heat is applied, and a gas flow isdirected through the interior of the main housing 204, for instance, byapplying a negative pressure to the proximal end downstream of the mainhousing 204 and the secondary housing 306. For example, the heaterincreases the temperature of the sample trap 120 to about 190-200° C.within about 10 seconds. Under the heating and gas flow, the gaseousmoieties and any particle moieties are released from the sample trap 120and collected by the TD tube 140 downstream. A LN2 cooling systemprovides the LN2 cooling coil 160 wrapped around the TD tube 140. Oncethe cooling temperature reaches below about 10° C., a sample pump isactivated to apply the negative pressure.

The adsorbent resin in the TD tube 140 disposed downstream of thesecondary housing 306 collects vapor-phase sample and any particlesample collected in the sample trap 120 that are released by the heatingand gas flow therethrough. In one embodiment, the TD tube 140 collectssample at a gas flow rate of about 50-100 mL/min for about 2-4 minutes.Vapor-phase and any micrometer-sized particle samples are collectedusing the TD collector 140 connected to the proximal end 346 of thesecondary housing 306. Some of the target analytes in explosive vaporsampling include high volatile organic compounds (e.g., MNT, NG, EGDN,and DMNB (taggant)).

The TD tube 140 is then separated from the TED and inserted directlyinto a TD-GC/MS. For a reusable TD tube, this desorption step servesalso as a regeneration step for the TD tube 140. As such, the TD tube140 is subsequently reconnected to the housing 104, 106 of the TED, andthe device is ready for another round of sample taking.

Thermal Desorption-Gas Chromatography/Mass Spectrometry (TD-GC/MS)

Once the sample trap 120 is heated and analyte is collected in the TDcollector 140, the TD collector (e.g., TD tube) 140 can be then analyzedby inserting it directly into the thermal desorption-gaschromatography/mass spectrometer (TD-GC/MS) for analysis of thecollected sample. A TDS (thermal desorption system) is coupled onto theGC injection port and the TD tube is inserted in the TDS. The vaporizedanalytes are re-tapped into a PTV (Programmed Temperature Vaporizer),which is set at about −40° C. The specified end temperature may be setat about 280° C. and the PTV is rapidly raised temperature ramp rate at12° C./second. Once the PTV is reached at the end temperature at about280° C. the operation system activates the MS to collect data.

The inventive concepts taught by way of the examples discussed above areamenable to modification, rearrangement, and embodiment in several ways.Accordingly, although the present disclosure has been described withreference to specific embodiments and examples, persons skilled in theart will recognize that changes may be made in form and detail withoutdeparting from the spirit and scope of the disclosure.

The claims define the invention and form part of the specification.Limitations from the written description are not to be read into theclaims.

An interpretation under 35 U.S.C. § 112(f) is desired only where thisdescription and/or the claims use specific terminology historicallyrecognized to invoke the benefit of interpretation, such as “means,” andthe structure corresponding to a recited function, to include theequivalents thereof, as permitted to the fullest extent of the law andthis written description, may include the disclosure, the accompanyingclaims, and the drawings, as they would be understood by one of skill inthe art.

To the extent the subject matter has been described in language specificto structural features and/or methodological steps, it is to beunderstood that the subject matter defined in the appended claims is notnecessarily limited to the specific features or steps described. Rather,the specific features and steps are disclosed as example forms ofimplementing the claimed subject matter. To the extent headings areused, they are provided for the convenience of the reader and are not betaken as limiting or restricting the systems, techniques, approaches,methods, devices to those appearing in any section. Rather, theteachings and disclosures herein can be combined, rearranged, with otherportions of this disclosure and the knowledge of one of ordinary skillin the art. It is the intention of this disclosure to encompass andinclude such variation. The indication of any elements or steps as“optional” does not indicate that all other or any other elements orsteps are mandatory.

What is claimed is:
 1. A thermal extraction apparatus comprising: ahousing having a gas inlet and a gas outlet to receive a gas flowthrough the housing from the gas inlet to the gas outlet, and a sideopening to receive a sample collector into a sample collector location,the sample collector having a sample collector adsorbent containing avapor sample; a pump to generate the gas flow; a heater to heat thesample collector adsorbent of the sample collector to a temperaturesufficient to release the vapor sample; a thermal desorption (TD) tubeconnected with the gas outlet of the housing to receive the gas flowdownstream of the sample collector and collect the vapor sample releasedfrom the sample collector adsorbent of the sample collector; and, acooling member in heat exchange with the TD tube to cool the TD tube;the housing including an upstream frustoconical cavity between the gasinlet and the sample collector location increasing in cross-sectionalarea from the gas inlet to the sample collector location.
 2. The thermalextraction apparatus of claim 1, wherein the heater is disposed in thehousing and the heater includes an upstream heating member upstream ofthe sample collector location for receiving the sample collector and adownstream heating member downstream of the sample collector location;and, wherein the thermal extraction apparatus further comprises atemperature control unit configured to control an upstream temperatureof the upstream heating member and a downstream temperature of thedownstream heating member to be lower than the upstream temperature. 3.The thermal extraction apparatus of claim 2, further comprising: anupstream thermometer coupled with the housing to measure the upstreamtemperature which is used as feedback by the temperature control unit tocontrol thermal output of the upstream heating member; and, a downstreamthermometer coupled with the housing to measure the downstreamtemperature which is used as feedback by the temperature control unit tocontrol thermal output of the downstream heating member.
 4. The thermalextraction apparatus of claim 2, wherein the cooling member comprises acoil around the TD tube and having a cooling fluid flowing through thecoil to cool the TD tube to a temperature of about 0-10° C.
 5. Thethermal extraction apparatus of claim 2, wherein the temperature controlunit is configured to control an upstream temperature of the upstreamheating member to about 200° C. and a downstream temperature of thedownstream heating member to about 190° C.
 6. The thermal extractionapparatus of claim 1, wherein the housing includes a downstreamfrustoconical cavity between the sample collector location and the gasoutlet decreasing in cross-sectional area from the sample collectorlocation to the gas outlet.
 7. A thermal extraction apparatuscomprising: a housing having a gas inlet and a gas outlet to receive agas flow through the housing from the gas inlet to the gas outlet, andan insertion port to receive a sample collector into a sample collectorlocation, the sample collector having a sample collector adsorbentcontaining a vapor sample; a pump to generate the gas flow; heatingmeans for heating the sample collector adsorbent of the sample collectorto a temperature sufficiently high to facilitate release of the vaporsample from the sample collector adsorbent of the sample collector; and,a thermal desorption (TD) tube connected with the gas outlet of thehousing to receive the gas flow downstream of the sample collector andcollect the vapor sample released from the sample collector adsorbent ofthe sample collector; the housing including an upstream frustoconicalcavity between the gas inlet and the sample collector locationincreasing in cross-sectional area from the gas inlet to the samplecollector location.
 8. The thermal extraction apparatus of claim 7,further comprising: cooling means for cooling the TD tube to atemperature sufficiently low to facilitate collection of the vaporsample released from the sample collector.
 9. The thermal extractionapparatus of claim 8, wherein the cooling means cools the TD tube to atemperature of about 0-10° C.
 10. The thermal extraction apparatus ofclaim 7, wherein the heating means heats an upstream portion of thehousing upstream of the insertion port to an upstream temperature ofabout 200° C. and a downstream portion of the housing downstream of theinsertion port to a downstream temperature of about 190° C.
 11. Thethermal extraction apparatus of claim 7, wherein the housing includes adownstream frustoconical cavity between the sample collector locationand the gas outlet decreasing in cross-sectional area from the samplecollector location to the gas outlet.
 12. A thermal extraction methodcomprising: placing a sample collector, which has a sample collectoradsorbent containing a vapor sample, inside a housing via a side openinginto a sample collector location; heating the sample collector adsorbentof the sample collector to a temperature sufficiently high to facilitaterelease of the vapor sample from the sample collector adsorbent; and,directing a gas flow through a gas inlet of the housing through thesample collector adsorbent of the sample collector through a gas outletof the housing to a thermal desorption (TD) tube connected with the gasoutlet of the housing to receive the gas flow downstream of the samplecollector and collect the vapor sample released from the samplecollector adsorbent of the sample collector inside the TD tube; thehousing including an upstream frustoconical cavity between the gas inletand the sample collector location increasing in cross-sectional areafrom the gas inlet to the sample collector location.
 13. The thermalextraction method of claim 12, further comprising: cooling the TD tubeto a temperature sufficiently low to facilitate collection of the vaporsample released from the sample collector.
 14. The thermal extractionmethod of claim 13, wherein the TD tube is cooled to a temperature ofabout 0-10° C.
 15. The thermal extraction method of claim 13, whereincooling the TD tube comprises placing a coil around the TD tube andflowing a cooling fluid through the coil to cool the TD tube to atemperature of about 0-10° C.
 16. The thermal extraction method of claim12, wherein heating the sample collector adsorbent of the samplecollector comprises heating the housing in a region adjacent the samplecollector to a temperature of at least about 200° C.
 17. The thermalextraction method of claim 12, wherein heating the sample collectoradsorbent of the sample collector comprises heating the housing in anupstream region adjacent the sample collector to an upstream temperatureof about 200° C. and heating the housing in a downstream region adjacentthe sample collector to a downstream temperature of about 190° C. 18.The thermal extraction method of claim 17, further comprising: placingan upstream heater in the upstream region of the housing to heat theupstream region and placing a downstream heater in the downstream regionof the housing to heat the downstream region.
 19. The thermal extractionmethod of claim 18, further comprising: measuring the upstreamtemperature of the housing and using the measured upstream temperatureas feedback to control thermal output of the upstream heater; and,measuring the downstream temperature of the housing and using themeasured downstream temperature as feedback to control thermal output ofthe downstream heater.
 20. The thermal extraction method of claim 12,further comprising: controlling the gas flow to have a gas flow rate ofabout 50-100 cc/minute for about 2-4 minutes through the samplecollector to the TD tube to collect the vapor sample from the samplecollector in the TD tube.
 21. The thermal extraction method of claim 12,further comprising: placing the TD tube having the vapor samplecollected therein into a Thermal Desorption-Gas Chromatography/MassSpectrometer (TD-GC/MS) for sample analysis of the vapor samplecollected in the TD tube.
 22. The thermal extraction method of claim 12,wherein the gas flow is directed through the gas inlet of the housingthrough the sample collector adsorbent of the sample collector at thesample collector location through the gas outlet of the housing to theTD tube; and wherein the housing includes a downstream frustoconicalcavity between the sample collector location and the gas outletdecreasing in cross-sectional area from the sample collector location tothe gas outlet.